The extracellular matrix (ECM) is known to provide scaffolding for cells while organizing the cells in three dimensions, as well as to provide essential information to regulate cell behavior. The field of tissue engineering strives to mimic both the form and function of these scaffolds to create compositions for optimal tissue repair and replacement. Collagen, and in particular Type I collagen, may be used in the field of tissue engineering due to its high availability in the body, conservation across tissues and species, biodegradability, and biocompatibility. Collagen is the most abundant molecule of the ECM and is responsible for the majority of the mechanical properties of several tissues. The in vivo form of collagen is a triple-helix center region capped at both ends by randomly organized telopeptides and contains natural molecular cross-links, which link the triple helices together into a branched network.
To date, collagen scaffolds known in the art have typically been utilized in the form of atelocollagen, which is characterized by the removal of telopeptides and of natural molecular cross-links, thus resulting in mechanical instability that limits its use as a larger sized implant. The instability of atelocollagen has led to a need for exogenous cross-linking strategies to return the collagen to a stronger, polymeric scaffold state. These cross-linking strategies, ranging from dehydrothermal and chemical treatments to copolymerization with other materials, have had varying success at increasing the stiffness of the collagen matrix, but undesirably affect the ability to mimic the in vivo structure and functionality of the collagen. Furthermore, the density of atelocollagen matrices has been limited by the starting collagen material (usually on the order of a maximum of 5-10 mg/mL), which is much less than the collagen concentration of 30-40 mg/mL found in connective tissues in vivo. This observation is of vital importance because matrix stiffness, a product of the collagen concentration, has been shown to directly impact the regulation of cell proliferation, migration, and differentiation.
Plastic compression has been performed on atelocollagen to force the fluid component out of the matrix, thus retaining the solid collagen component. These scaffolds have been shown to hold their shape and have higher mechanical properties compared to uncompressed atelocollagen gels. However, the compression processes used to create the atelocollagen compressed scaffolds are extreme processes, resulting in the excretion of nearly all of the fluid that can be removed from the scaffolds. As a result, the final material for the atelocollagen scaffold is often quite small, on the order of less than 100 μL of total volume following compression. In addition, it has been shown that the compression processes can reduce the cellular viability of the scaffolds and damage the natural matrix architecture that is essential to impact the regulation of cellular functions such as proliferation, migration, and differentiation.
Accordingly, there exists a need for alternative compression techniques to form collagen compositions that provide advantages in the field of tissue engineering. Surprisingly, the inventors have found that alternative collagen compression techniques can provide a gradient of a physical property within the composition, resulting in multiple regions within the collagen composition that can be utilized to regulate cellular functions.
The engineered collagen compositions of the present disclosure provide several advantages compared to those known in the art. First, the engineered collagen compositions of the present disclosure possess improved mechanical properties compared to those in the art. In particular, the engineered collagen compositions of the present disclosure are not as fragile and have improved strength. Furthermore, the engineered collagen compositions of the present disclosure have improved resistance to degradation.
Second, manufacturing the engineered collagen compositions of the present disclosure allows for induction of high level interfibril associations prior to compression of the compositions. This step allows for control of important mechanical properties prior to creation of the final compositions, and the controlled mechanical properties are retained following compression of the final compositions.
In addition, a multitude of mechanical properties can be “tuned” for the engineered collagen compositions of the present disclosure prior to compression. As a result, critical design features of collagen scaffolds can be optimized for purposes of predictably inducing desired cellular mechanisms and responses for repair and replacement in patients.
In one embodiment described herein, an engineered collagen composition is provided. The engineered collagen composition comprises collagen, wherein the collagen composition is compressed to form a gradient of at least one physical property.
In another embodiment, a method of treating a patient is provided. The method comprises the step of implanting the engineered collagen composition of the present disclosure into the patient.
In another embodiment, a method of manufacturing an engineered collagen composition is provided. The method comprises the step of compressing the collagen composition to form the gradient of at least one physical property.
Any of the embodiments described in the following clause list are considered to be part of the invention:
1. An engineered collagen composition comprising collagen, wherein the collagen composition is compressed to form a gradient of at least one physical property.
2. The engineered collagen composition of clause 1, wherein the collagen is solubilized from tissue.
3. The engineered collagen composition of clause 1 or clause 2, wherein the collagen composition is a medical graft.
4. The engineered collagen composition of any one of clauses 1 to 3, wherein the collagen is polymerizable collagen.
5. The engineered collagen composition of any one of clauses 1 to 4, wherein the collagen is Type I collagen.
6. The engineered collagen composition of any one of clauses 1 to 5, wherein the collagen is unnatural collagen.
7. The engineered collagen composition of any one of clauses 1 to 6, wherein the collagen is oligomeric collagen.
8. The engineered collagen composition of any one of clauses 1 to 6, wherein the collagen comprises oligomeric collagen.
9. The engineered collagen composition of any one of clauses 1 to 6, wherein the collagen consists essentially of oligomeric collagen.
10. The engineered collagen composition of any one of clauses 1 to 6, wherein the collagen consists of oligomeric collagen.
11. The engineered collagen composition of any one of clauses 1 to 6, wherein the collagen comprises monomeric collagen.
12. The engineered collagen composition of any one of clauses 1 to 6, wherein the collagen comprises atelocollagen.
13. The engineered collagen composition of any one of clauses 1 to 6, wherein the collagen comprises oligomeric collagen and atelocollagen.
14. The engineered collagen composition of any one of clauses 1 to 6, wherein the collagen comprises oligomeric collagen, monomeric collagen, and atelocollagen.
15. The engineered collagen composition of any one of clauses 1 to 14, wherein the collagen is selected from the group consisting of pig skin collagen, bovine collagen, and human collagen.
16. The engineered collagen composition of any one of clauses 1 to 14, wherein the collagen is synthetic collagen.
17. The engineered collagen composition of any one of clauses 1 to 15, wherein the collagen is recombinant collagen.
18. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 1 mg/ml to about 500 mg/ml.
19. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 1 mg/ml to about 400 mg/ml.
20. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 1 mg/ml to about 300 mg/ml.
21. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 1 mg/ml to about 200 mg/ml.
22. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 1 mg/ml to about 100 mg/ml.
23. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 2 mg/ml to about 5 mg/ml.
24. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 3.5 mg/ml.
25. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 4 mg/ml to about 10 mg/ml.
26. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 5 mg/ml.
27. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 10 mg/ml to about 20 mg/ml.
28. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 12 mg/ml.
29. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 20 mg/ml to about 30 mg/ml.
30. The engineered collagen composition of any one of clauses 1 to 17, wherein the collagen is present at a concentration of about 24 mg/ml.
31. The engineered collagen composition of any one of clauses 1 to 30, wherein the composition further comprises a polymer.
32. The engineered collagen composition of any one of clauses 1 to 31, wherein the composition further comprises a co-polymer.
33. The engineered collagen composition of any one of clauses 1 to 32, wherein the gradient is a compression-induced gradient.
34. The engineered collagen composition of any one of clauses 1 to 33, wherein the compression is a confined compression.
35. The engineered collagen composition of any one of clauses 1 to 33, wherein the compression is a variable compression.
36. The engineered collagen composition of any one of clauses 1 to 33, wherein the compression is a physical compression.
37. The engineered collagen composition of any one of clauses 1 to 33, wherein the compression is centrifugation.
38. The engineered collagen composition of any one of clauses 1 to 33, wherein the compression is ultracentrifugation.
39. The engineered collagen composition of any one of clauses 1 to 33, wherein the compression is evaporation.
40. The engineered collagen composition of any one of clauses 1 to 33, wherein the compression is aspiration.
41. The engineered collagen composition of clause 40, wherein the aspiration is vacuum aspiration.
42. The engineered collagen composition of any one of clauses 1 to 41, wherein the compression is a physical force from at least one direction.
43. The engineered collagen composition of any one of clauses 1 to 41, wherein the compression is a physical force from two or more directions.
44. The engineered collagen composition of any one of clauses 1 to 41, wherein the compression is a physical force from three or more directions.
45. The engineered collagen composition of any one of clauses 1 to 41, wherein the compression is a physical force from four or more directions.
46. The engineered collagen composition of any one of clauses 1 to 45, wherein the physical property is density.
47. The engineered collagen composition of any one of clauses 1 to 45, wherein the physical property is stiffness.
48. The engineered collagen composition of any one of clauses 1 to 45, wherein the physical property is fibril orientation.
49. The engineered collagen composition of any one of clauses 1 to 45, wherein the physical property is collagen microstructure.
50. The engineered collagen composition of any one of clauses 1 to 45, wherein the physical property is porosity.
51. The engineered collagen composition of any one of clauses 1 to 45, wherein the physical property is the ratio of collagen type.
52. The engineered collagen composition of any one of clauses 1 to 51, wherein the composition comprises at least two regions.
53. The engineered collagen composition of clause 52, wherein at least one region comprises a high fibril density, and wherein at least one other region comprises a low fibril density.
54. The engineered collagen composition of clause 52, wherein at least one region comprises a high stiffness, and wherein at least one other region comprises a low stiffness.
55. The engineered collagen composition of clause 52, wherein at least one region comprises a high porosity, and wherein at least one other region comprises a low porosity.
56. The engineered collagen composition of clause 52, wherein at least one region comprises an aligned fibril orientation, and wherein at least one other region comprises a random fibril orientation.
57. The engineered collagen composition of any one of clauses 1 to 56, wherein the composition further comprises cells.
58. The engineered collagen composition of clause 57, wherein the cells are stem cells.
59. The engineered collagen composition of any one of clauses 1 to 58, wherein the composition is a fibrous foam.
60. The engineered collagen composition of any one of clauses 1 to 58, wherein the composition is a hydrogel.
61. The engineered collagen composition of any one of clauses 1 to 60, wherein the composition is a collagen-fibril matrix.
62. The engineered collagen composition of any one of clauses 1 to 61, wherein the composition is a porous matrix.
63. The engineered collagen composition of any one of clauses 1 to 62, wherein the composition further comprises fluid.
64. The engineered collagen composition of clause 63, wherein the fluid percentage is present between about 25% to about 99%.
65. The engineered collagen composition of any one of clauses 1 to 64, wherein the composition is lyophilized.
66. A method of treating a patient comprising the step of implanting the engineered collagen composition of any one of the preceding clauses into the patient.
67. A method of manufacturing an engineered collagen composition of any one of the preceding clauses comprising the step of compressing the collagen composition to form the gradient of at least one physical property.
68. The method of clause 67, wherein the method comprises the step of polymerizing the collagen prior to compressing the collagen composition into a defined shape.
69. The method of clause 67 or clause 68, wherein the method comprises the step of tuning the physical property prior to compressing the collagen composition into a defined shape.
70. The method of any one of clauses 67 to 69, wherein the compression is modulated through patterned fluid removal.
71. The method of any one of clauses 67 to 69, wherein the compression is modulated through patterned air removal.
72. The method of any one of clauses 67 to 71, wherein the step of compressing removes fluid from the composition.
73. The method of any one of clauses 67 to 72, wherein the defined shape is a tube.
74. The method of any one of clauses 67 to 72, wherein the defined shape is a sheet.
75. The method of any one of clauses 67 to 72, wherein the defined shape is a sphere.
76. The method of any one of clauses 67 to 72, wherein the defined shape is a slab.
77. The method of any one of clauses 67 to 72, wherein the defined shape is a cylinder.
78. The method of any one of clauses 67 to 72, wherein the defined shape is a cone.